In painting systems for painting components (e.g., motor vehicle bodywork components), conventionally, for conveying the coating agent to be applied, coating agent pumps are used which can be configured, for example, as diaphragm pumps. When the coating agent to be conveyed is changed (e.g., on a change of colour in a painting system), the coating agent pump must be cleaned, wherein the previously conveyed coating agent must be removed as completely as possible from the coating agent pump, because the previously conveyed coating agent otherwise causes contamination of the new coating agent. For this purpose, it is known from the prior art to rinse the coating agent pump with a rinsing agent, wherein the rinsing agent is fed in via the pump inlet and leaves the coating agent pump again via the pump outlet.
A disadvantage of this known cleaning method for cleaning a coating agent pump is that a residue of the previously conveyed coating agent and/or cleaning agent remains in the coating agent pump.
This has the consequence, in the first place, that when the coating agent is changed, part of the new coating agent must initially be discarded, because the new coating agent is initially contaminated with residues of the old coating agent and/or cleaning agent. Because new coating agent must be rejected on a change of coating agent, the coating agent consumption is unavoidably increased.
In the second place, a coating agent change is herein not possible without interruption because in addition to the rinsing of the coating agent pump, some time elapses until the new coating agent is no longer contaminated with the old coating agent and/or cleaning agent. A disadvantage therefore also lies in the relatively long cleaning pause on a change of coating agent.
Furthermore, it must be considered that coating agent residues remaining in the coating agent pump after a cleaning process must be discarded, which also leads to an increased coating agent use.
From DE 198 27 213 A1, there is known a coating agent pump which has a plurality of pump inlets, wherein the cleaning of the coating agent pump takes place in that cleaning agent is fed into the coating agent pump via one of the pump inlets. This coating agent pump also has the disadvantages discussed above.
With regard to the prior art, reference is also made to DE 100 29 928 A1.